Can old brewed coffee make you sick?
I have a friend who brews a pot of coffee once a week and drinks a cup a day (warmed in the microwave) until it's gone. Sometimes that same pot sits on his counter for more than a week. I notice that he is sick quite often -- is it possible that he is getting sick from doing this?
Plenty of people keep cold coffee in the fridge for a week or so, and then microwave a cup or two each day.
Not exactly the best way to enjoy the finer flavors of a gourmet coffee, but it works for some people.
That's the amazing thing about coffee...some people love it like they love a fine wine, while others are just happy for a hot brew with a nice caffeine kick.
That said, if he doesn't keep it in the fridge, I would be a little more concerned. I'm not a doctor or any kid of medical practitioner, but I'm guessing there are some unpleasant moulds that would be happy to take residence in coffee that is sitting around at room temperature.
I would encourage your friend either to keep the coffee in the fridge, or brew more often.